Question: $ E = \left[\begin{array}{rrr}1 & 0 & 1 \\ 0 & 2 & 1 \\ 2 & 1 & 0\end{array}\right]$ What is $ E^{-1}$ ?
Explanation: $ = \left[\begin{array}{rrr}\frac{1}{5} & -\frac{1}{5} & \frac{2}{5} \\ -\frac{2}{5} & \frac{2}{5} & \frac{1}{5} \\ \frac{4}{5} & \frac{1}{5} & -\frac{2}{5}\end{array}\right]$